lol what do you think myself and the mechanic did? You cant tell a turbo bearing has a flat spot by free spinning it. The flat spot was smaller than a pin-head and the turbo rebuilder had to show me where it was once it was pulled apart.
It only takes a spec of dirt etc to create a flat spot, and its not going to affect the spinning or play of the turbo. Only once its running on the car you can clearly hear the sound